Challenge 3: A Macro Lost to a Default Save — Solution Walkthrough

What happened:

The workbook was recorded with a macro but never saved as a
Macro-Enabled Workbook (.xlsm) — it was left as a regular .xlsx file
(the default format Excel proposes for a new workbook). When the
colleague pressed Ctrl+S, Excel detected the file contained a macro
and showed a warning dialog asking whether to keep the macro (by
switching to .xlsm) or save without it (keeping .xlsx). Dismissing
that dialog without reading it — most likely by clicking "No" / "Use
the current format" out of habit, the same way one might dismiss a
routine confirmation prompt — chose the second option: the file saved
successfully as a normal .xlsx, but with every macro silently
stripped out in the process. The workbook itself is fine; the macro
specifically no longer exists anywhere in that saved file.

What they should have done differently when saving:

The very first time the workbook is saved after a macro is recorded,
use File > Save As (or the same dialog that appears from the warning)
and explicitly choose "Excel Macro-Enabled Workbook (*.xlsm)" as the
file type, rather than accepting the default .xlsx. Every SUBSEQUENT
save with Ctrl+S then keeps working normally, since the file is
already the correct macro-enabled type and Excel has no reason to
show that warning again.

Notes:
- This is exactly the gotcha this chapter's own warning box
  describes — the macro isn't corrupted or hidden somewhere, it's
  genuinely gone from that saved file, and the only real fix is to
  re-record it (or restore an earlier .xlsm backup, if one exists)
  and this time save it correctly from the start.